Waveguide hybrid junctions



Jan. 8, 1963 R. M. WHITEHORN WAVEGUIDE HYBRID JUNCTIONS Filed June 2'7,1960 Fig.2

IN V EN TOR. flown A1 W s #910712 iifiil ifi h Patented Jean. 8, ll5

3,972,859 WAVEGUEE HYBRID EUNQ'TEGNS Richard M. Whitehorn, Menlo Farls,Caiif assigns: to Varian Associates, Pain Alto, Calii, a corporation ofCalifornia Filed June 27, 1960, Ser. No. 38,355 9 Claims. (U. 325446)units of minimum size and weight are desired.

it is the principal object of the present invention to provide a compactand light-weight hybrid junction possessing requency insensitivebalanced properties.

One feature of the present invention is the provision Of a balancedhybrid junction comprising a waveguide capable of propagating in twoorthogonal modes and adapted to accommodate a first polarized wavethrough one end thereof and a second perpendicularly polarized wavethrough a portion of waveguide surface adjacent said one end.

Another feature of the present invention is the provision of a balancedjunction according to the previous paragraph, wherein a collinear pairof crystal rectifie-rs is interiorly inserted through said waveguide inthe direction of polarization of said first wave to provide a balancedmicrowave mixer.

Still another feature of the present invention is the provision of amixer assembly comprising a mixer in accordance with the precedingparagraph in combination with a crystal protector tube secured at saidone end of said waveguide and a refiex klystron oscillator secured atsaid waveguide surface portion.

These and other features and advantages of the present invention will bemore apparent upon a perusal of the following specification taken inconnection with the accompanying drawings, wherein:

FIG. 1 is an isometric view of a microwave mixer assembly in accordancewith the present invention,

PEG. 2 is a cross-sectional view taken along line 22 in FIG. 1, and

' FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2.

In the mixer assembly of FIG. 1, a section of rectangular waveguide 1 ismounted on a base plate 2 and sup ports the rear window of acommercially available crystal protector tube 3-for example, modelMA34OA manufactured by Microwave Associates, Inc., of Burlington,

Massachusettsby means of a flange 4 at the front end of the waveguidesection 1. The front window of the crystals protector tube 3 is centeredin an opening 5 formed in the mounting flange 5 which is brazed to thefront end of the base plate 2 and is adapted to receive energy'throughan abutting choke flange (not shown).

Secured to the bottom of Waveguide section 1 is a commercially availablereflex klystron local oscillator 6,

a for example, model VA-2l7S manufactured by Varian Associates at PaloAlto, California, with an operating frequency range of 8.5 to 9.6 kmc.As best seen in FIG. 3, the output cavity resonator 7 of tube 6 iscoupled to waveguide section 1 via a longitudinally extending iris 8formed in the base plate 2, the amount of power coupled through saidiris being controlled by an attenuator card 9 slideably engaged in aslot milled through the underside surface of the plate 2. The tube 6 istuned by means of a tuning plunger 10 slideably inserted in the outputcavity 7 and actuated by the rotation of an externally threaded tuningknob ll. Spur gear 12 which controls the setting of potentiometer 12 ismated to the external threads of knob 11 so that the repeller electrodevoltage of tube 6 determined by potentiometer 12 is adjusted tocorrespond with the setting of the tuning plunger 1%. A small screw 13extends through tube mating flange '7 to provide a factory adjustment ofthe tuning range of the klystron.

A pair of crystal rectifiers 143 vertically extending through waveguidesection 1 are secured under tension at the oppositely poled inwardterminals thereof by split cylindrical conductor 15. The exteriorterminal of each rectifier is secured under tension by a hat connector16 mounted in insulated relation with respect to the waveguidesection 1. p

- The DC. current in the crystals 14 is monitored by means of thevoltage appearing at monitoring lugs 19 attached to each hat connector16 thereby providing a check on the coupling of energy from the localoscillator to the crystals and permitting the attenuator card 9 to bepositioned so that the current is within a range of optimum crystalperformance. Resistor 17, connected between monitoring lug l9 and groundlug 2% attached to waveguide it, provides a DC. path to ground acrosswhich is established the current measuring voltage applied to terminal19, and is chosen to establish a minimum bias across the crystalsconsistent with the requirements of the voltage measuring instrument.The DC. crystal current components which would produce undesirableleakage fields are filtered from terminals 19 by means of the shuntcapacitor 18 connected in parallel terminals 19 by means of the shuntcapacitor 18 connected in parallel with resistor 17.

The outwardly extending rearward flange 15' of conductor i5 is securedvia a thin mica insulating sheet 21 to a partition 22 of the waveguide land is contacted by screw 23 threadably inserted therein throughphenolic insulating shoulder Washer 24 seated in an opening of partition22. The screw 23 secures lug 25 to provide an output LP. terminal whichis protected by means of a cement casing 25.

Also disposed within the waveguide ll are a dielectric partition 27spaced rearwardly of the crystal protector tube 3 to provide an inputimpedance transformer, and a dissipative fin 23 as of rnetallized epoxyPiberglas projecting inwardly of the waveguide wall along theperpendicular bisector of the axes of crystal rectifier l4 and extendingbetween partitions 2'7 and flange 15 as indicated by the phantom linesin H6. 2.

in operation, a vertically polarized signal wave is transmitted throughthe crystal protector tube 3 undisturbed by fin 2d and provides electricfields extending in the same direction along the responsive axis of eachcrystal rectifier 14. A horizontally polarized local oscillator wave istransmitted through iris 8 and is perturbed by the fin 2% so thatelectric fields of opposite direction are produced along the axes of thecrystal rectifiers 14.

Since the relative phases between the local oscillator wave and thesignal wave in the separate crystals are reversed, the LP. beatfrequency component of the cur rent in the separate crystals areout-of-phase, whereas the relative phases between the local oscillatorwave and the noise due to local oscillator fluctuations are the same.Thus, local oscillator noise is balanced out of the difference in thecrystal currents which flows along conductors l5 and 23 to LP. terminal25. The high frequency signal and local oscillator components arebypassed to ground through the capacitance between conaeraseo ductors 23and conductor 22 thereby providing a frequency insensitive, balancedoutput at terminal 25.

Several advantageous features are to be noted with respect to theconfiguration of waveguide connections illustrated in FIG. 1. Both waveenergy sources may be concentrated at one end of the waveguide forsimplicity of access. The two input connections are of the same relativeposition and polarity as in the conventional magic- T junction, so thata-minimum of modifiication in the design of existing waveguideassemblies is necessary. Still further, the total energy input to thecrystal rectifiers is fromone side only, thereby allowing considerablefreedom in the mounting of the crystals; for example,

crystals designed for extremely high frequencies which are housed in amounting that is large in relation to the Waveguide size, and which mayincorporate a shorting plane on one side, may be used.

It should be further noted that the electromagnetic energy propagatedaxially down waveguide 1 is established in two orthogonal modes, onecorresponding to each input signal, and that the modes are perturbedsothat the electric fields of both modes are asymmetrical about allequipotentials of one mode but symmetrical about an equipotential of theother mode. As explained in greater detail inv my copending US. patentapplication, Serial No. 862,356, filed December 28, 1959 now US. Patent3,666,296, issued November 27, 1962, such a mode pattern establishes afirst waveguide region in which a directional component of the electricfields of the two modes will be in-phase and a second waveguide regionin which the electric field of the two modes will be out-of-phase. Thus,balanced hybrid junctions having a variety of well-known applicationsare possible by providing appropriate connections directionallyresponsive to the electric fields in these regions, directly or by meansof concomitant magnetic fields. Such connections may include, forexample: a single mode waveguide, or a crystal rectifier (as in theillustrative example), capacitor, absorber or other device inserteddirectly into the waveguide. The described mode pattern permits theconnections to be collinearly disposed and is therefore adaptable tosimple and practical manufacturing techniques.

Various alternative techniques are available for establishing thedesired asymmetrical orthogonal mode pattern including, for example, theuse of a metallic projcction extending from the waveguide Wall, or anasymmetrical wave source coupling. Still further, alternative wa eguidecross-sectional configurations capable of supporting orthogonal modes,including, for example, a circular cross section, may be used.

Since many changes could be made in the above construction and manyapparently widely difierent embodiment of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A balanced hyb id junction comprising a waveguide capable of axiallypropagating in two orthogonal modes, means located at one end of saidwaveguide for accommodating a first electromagnetic wave propagating inone of said modes, means located on the surface of said waveguideadjacent said one end for accommodating a second electromagnetic wavepropagating in the other of said modes, a pair of connections spacedfrom said one end of said waveguide and directionally responsive to theelectric fields of said modes, and means for perturbing said modes toproduce electric fields of opposite direction in each connection withone mode and electric fields of the same direction in eachconnection-with the other mode.

2. A balanced microwave mixer comprising a section of waveguide capableof axially propagating in two orthogonal modes, means located at one endof said waveguide scction for accommodating a first electromagnetic wavepropagating in one of said modes, means located on the surface of saidwaveguide adjacent said one end for accommodating a secondelectromagnetic wave propagating in the other of said modes, a pair ofcrystal rectifiers extending inwardly of said waveguide at a positionremote from said one end, means for perturbing the electric fields insaid waveguide to establish electric fields of opposite direction ineach crystal rectifier with one mode and electric fields of the samedirection in each crystal rectifier with the other mode, and means forcombining the signals in said crystal rectifier to produce a balancedbeat frequency output.

3. A balanced microwave mixer according to claim 2 wherein the inwardlyextending terminals of said crystal rectifiers are of opposite polarity,and further including an output connector receiving said inwardlyextending terminals.

4. A balanced microwave mixer according to claim 3 wherein said crystalrectifiers are collinearly disposed in the polarization direction ofsaid first electromagnetic wave. 7

5. A microwave according to claim 4 further including means capacitivelycoupling said output connector to said waveguide section for bypassingthe high frequency components of said first and second electromagneticwaves.

6. The combination of claim 4 further comprising a crystal protectortube secured to said one end of said waveguide section and a reflexklystron local oscillator tube secured to said adjacent waveguidesurface.

7. The combination of claim 5 wherein the exterior terminals of saidcrystal rectifiers are insulated from said waveguide section, andfurther including a resistor connected between said exterior terminalsand said waveguide across which is developed a DC. crystal currentmonitoring voltage and a capacitor connected in parallel with saidresistor for bypassing A.C. current components.

8. The combination of claim 5 wherein said perturbing means comprises adissipative fin projectinginwardly of the wall of said waveguide alongthe perpendicular bisector of the axes of said crystal rectifiers.

9. The combination of claim 8 furtherfincluding a partition at the endof the waveguide opposite to said one end, and wherein said outputconnector includes a conductor extending through said partition ininsulated relation therewith.

References Cited in the file of this patent UNITED STATES PATENTS2,547,378 Dicke Apr. 3, 1951 2,679,582 Edwards May 25, 1954 2,810,984Blitz Oct. 22, 1957 2,813,972 Anderson et al Nov. 19, 1957 2,832,885Brett Apr. 29, 1958 2,859,626 Tomiyasu Sept. 2, 1958 2,863,042 Sanderset al Dec. 2, 1958 OTHER REFERENCES Corbell: Microwave Mixer forAirborne Radar, Electronics, pages -71, FebruaryS, 1960.

UNITED STATES PATENT OFFICE TIETTTCATE GT 'EQTQN January 8 1963 PatentN00 3 012 850 Richard M, Whitehorn It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected belowa Column l line 60after "receive" insert wave eolumn 2 line 31 v for D061, read A000 3lines 35 and :36 strike out terminals 19 by means of the shunt capacitor18 eonnented in parallel"; column 41 line 29 after; "microwave" insertWe mixer e Signed and sealed this 10th day of September 1963,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Ufficer DAVID L. LADD Commissioner of PatentsUNITED STATES PATENT oTTTcE TIERHHQATE GE QQRREGHQN Patent N00 3 012 850January 8 1963 Richard M, Whitehorn It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected belowa Column l line 60after "receive" insert wave eolumn 2 line 31 v for D061, read A000 3lines 35 and :36 strike out terminals 19 by means of the shunt capacitor18 aonnented in parallel"; column 41 line 29 after; "microwave" insertWe mixer e Signed and sealed this 10th day of September 1963,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Ufficer DAVID L. LADD Commissioner of PatentsUNITED STATES PATENT OFFICE @EREFCATE l QORRECTION Patent No, 3 OT2 85OJanuary 8 1963 Richard M Whitehorn It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected belowa Column 1 line 6Oafter "receive" insert W wave column 2 line 31 for "DQCQ'" read ADC},lines 35 and 36 strike out terminals 19 by means of the shunt oapaoitorl8 commented in parallel; column 4 line 29 afters microw ave" insertmixer e Signed and sealed this 10th day of September 1963.,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents

1. A BALANCED HYBRID JUNCTION COMPRISING A WAVEGUIDE CAPABLE OF AXIALLYPROPAGATING IN TWO ORTHOGONAL MODES, MEANS LOCATED AT ONE END OF SAIDWAVEGUIDE FOR ACCOMMODATING A FIRST ELECTROMAGNETIC WAVE PROPAGATING INONE OF SAID MODES, MEANS LOCATED ON THE SURFACE OF SAID WAVEGUIDEADJACENT SAID ONE END FOR ACCOMMODATING A SECOND ELECTROMAGNETIC WAVEPROPAGATING IN THE OTHER OF SAID MODES, A PAIR OF CONNECTIONS SPACEDFROM SAID ONE END OF SAID WAVEGUIDE AND DIRECTIONALLY RESPONSIVE TO THEELECTRIC FIELDS OF SAID MODES, AND MEANS FOR PERTURBING SAID MODES TOPRODUCE ELECTRIC FIELDS OF OPPOSITE DIRECTION IN EACH CONNECTION WITHONE MODE AND ELECTRIC FIELDS OF THE SAME DIRECTION IN EACH CONNECTIONWITH THE OTHER MODE.